Rotary piston engine



Oct. 29, 1963 H. o. SCHERENBERG 3,108,578

ROTARY PISTON ENGINE Filed Feb. 8, 1962 2 Sheets-Sheet 1 FIG. I

INVENTOR. HANS O. SCHERENBERG BY M M A TTORNEYS.

Oct. 29, 1963 Filed Feb. 8, 1962' H. O. SCHERENBERG ROTARY PISTON ENGINE2 Sheets-Sheet 2 INVENTOR. HANS 0. SCHERENBERG xDw M637 ATTORNEYS.

United States Patent F 3,108,578 RGTARY PETGN ENGENE Hans 0.dcherenberg, Stuttgart-Heninaden, Germany,

assignor to Daimler-Benz Ahtiengesellschaft, Stuttgart- Unterturlrheim,Germany Filed Feb. 3, M62, Ser- No. 171,929 Ciaiins priority,application Germany Mar. 16, 1961 ii Claims. or. res-s The presentinvention relates to a rotary piston internal combustion engine oftrochoidal construction provided with a piston carrying out a rotarymovement about an eccentric arranged at the output shaft, in which, forpurposes of achieving the rotary movement of the piston at least atrochoidally-shaped guide cam is arranged at the housing or at thepiston and guide rollers are provided at the piston or at the housing,respectively, cooperating with this guide cam track.

In order to achieve the required predetermined rotational speed ratio ofthe output shaft and of the piston as required for practical operationof rotary piston internal combustion engines of trochoidal construction,it has been proposed heretofore to substitute, for the knowntransmission consisting of an internally toothed gear and an externallytoothed gear wheel, the arrangement of trochoidally shaped cam tracksand guide rollers cooperating therewith in order to gain space foroutput or driven shafts of larger diameter.

The present invention aims at a further advantageous development andimprovement of such transmissions consisting of cam tracks and guiderollers, and essentially consists in subdividing the cam track into twopartial cam tracks disposed one behind the other in the axial directionof the engine and cooperating with pairs of guide rollers whereby onepartial cam track is in operative engagement with the one guide rollerof the pair of guide rollers when high roller rotational speeds occurduring rotation of the piston whereas the other partial cam track is inoperative engagement with the other guide roller of the pair of guiderollers when relatively small roller rotational speeds occur.

As a guide roller runs along a cam track, there is imparted to the guideroller by reason of relatively large rotational speed differences thatoccur considerable accelerations and decelerations which may affectadversely the cam track of the guide roller and which jeopardize a safeguidance. The accelerations and decelerations acting on a guide rollerof the pair of guide rollers are reduced to such a considerable extentby the present invention that harmful effects on the guide rollers needno longer be expected.

According to a further feature of the present invention, the surfaceportions of the partial cam tracks which during certain phases ofoperation do not engage or come into contact with the guide rollers maybe set back or undercut with respect to the other surface portions, forexample, may be machined or ground by appropriate machinery to thedesired undercut or set back.

In order not to impair the guidance when the guidance is given up by ortransferred from one guide roller to the other, the beginning and end ofthe non-set back or nonundercut surface portions of the partial camtracks may be in operative connection with each other by web portionswhich come in contact or engage both guide rollers of a respective pair.The length and positions of these web portions may thereby be soselected that the accelerations and decelerations of the guide rollersare reduced to a minimum.

Accordingly, it is an object of the present invention to provide atransmission consisting of cam tracks and guide rollers for imparting toa rotary piston internal combustion engine of trochoidal constructionthe required rota- Patented Oct. 29, 1963 tional speed ratio betweenpiston and output shaft which efiectively eliminates the shortcomingsencountered with the prior art constructions by simple means that may bereadily manufactured without entailing substantial expenditures.

Another object of the present invention resides in the provision of arotary piston internal combustion engine of trochoidal constructionprovided with transmission means consisting of cam tracks and guiderollers for imparting to the rotary piston the desired speed relative tothe speed of the driven shaft in which the accelerations anddecelerations acting on the guide rollers are considerably reduced so asto minimize if not completely eliminate the harmful elfects that wouldotherwise occur at the cam tracks and/ or guide rollers withoutimpairing a safe and reliable guidance.

A further object of the present invention resides in the provision of arotary piston internal combustion engine provided with transmissionmeans consisting of cam track means and guide roller means forestablishing the predetermined rotary speed relative to the output shaftin which means are provided to assure proper guidance notwithstandingthe subdivision of the cam tracks into partial cam track. sections.

These and other objects, features and advantages of the presentinvention will become more obvious from the following description whentaken in connection with the accompanying drawing which shows, forpurposes of illustration only, one embodiment in accordance with thepresent invention, and wherein FIGURE l is a cross sectional viewthrough a rotary piston internal combustion engine of the type to whichthe present invention relates;

FlGURE 2 is an elevational view, on an enlarged scale, and partially incross section, taken in the direction of arrow II of FIGURE 1 andillustrating the cam track arrangement in accordance with the presentinvention, and

FIGURE 3 is an elevational view taken at right angles to FIGURE 2 in thedirection of arrow III of FIGURE 2.

Referring now to the drawing wherein like reference numerals are usedthroughout the various views to designate corresponding parts, and moreparticularly to FIGURE 1, the triangularly-shaped piston 2 is arrangedon an eccentric of the driven or output shaft 1 so as to rotate in thedirection of arrow 3 within the housing 5 provided with a two-arched camsurface or track 4. In order to achieve a rotary movement of the piston2 on the eccentric relative to the driven shaft 1 with the value of /3of the angular velocity of the shaft 1 required for proper operation ofthe illustrated embodiment, there is provided, instead of the usual geartransmission, the trochoidally-shaped cam track 6 arranged at onehousing side wall, possibly another cam track being also arranged at theoppositely disposed housing side wall, which cam track 6 cooperates withpairs of guide rollers 7 supported at the piston 2.

As shown in detail in FIGURES 2 and 3, the cam track generallydesignated by reference numeral 6 which is secured with the side wall 8thereof at the housing side wall in any suitable manner, consists of thetwo partial cam track sections 6' and 6" disposed one behind the otherin the axial direction. The guide roller '7' of the pair of guiderollers generally designated by reference numeral 7 cooperates with thepartial cam track section 6' and the guide roller 7" of the pair ofguide rollers 7 cooperates with the partial cam track section 6". In theillustrated embodiment three pairs of guide rollers 7 are providedthough, of course, the number of guide roller pairs may be varied. Thepairs of guide rollers 7 are rotatably supported in any suitable mannerknown in the prior art on hearing bolt members or bearing pins 9 whichin turn are supported at the lateral guide ring secured at the piston.

Both partial cam track sections 6' and 6" are provided with surfaceportions which come into engagement or contact with the guide rollers'7' and 7" during rotation of the piston. These surface portions whichwill be referred to as active surface portions are designated on the camtrack section 6 by reference numeral 11 and on the cam track portion 6by reference numeral 12. Additionally, the cam track sections 6' and 6"are provided with set-back or undercut surface portions which do notcome into engagement with the guide rollers 7' and 7" during rotation ofthe piston. These surface portions which will be referred to as inactivesurface portions are designated in connection with the partial cam tracksection 6 by reference numeral 11' and in connection with the partialcam track portion 6" by reference numeral 12.

The active surface portions 11 at the partial cam track section 6 aredisposed within an area in which relatively high rotational speeds occuron the part of the guide roller member 7' whereas the active surfaceportions 12 at the partial cam track section 6" are disposed within anarea in which relatively low rotational speeds of the guide rollers 7occur.

The non-set back surface portions, i.e., the active surface portions 11and 12 along which are guided the guide rollers 7 and 7", are connectedwith each other at the beginning and end thereof by web portions 13along which are guided simultaneously both guide rollers 7 and 7". Thelength of these web portions 13 in the circumferential direction and therespective position of these web portions are appropriately so selectedthat decelerations and accelerations of the guide rollers are reduced toa minimum.

During rotation of the piston, the latter is guided by means of theguide roller 7 along the surface portion 11 of the partial track section6 whereas, at the same time, the guide roller 7" passes freely over theset-back surface portion 12' of the partial cam track section 6". Uponreaching the web portion 13 both guide rollers 7' and 7" of each guideroller pair 7 carry out a guide function, and upon leaving the webportion 13 the guide roller 7" takes over the guidance along the surfaceportion 12 of the partial track section 6" whereas at the same time theguide roller 7' passes freely over the set-back surface portion 11 ofthe partial cam track section 6.

While I have shown and described one embodiment in accordance with thepresent invention, it is understood that the same is not limitedthereto, but is susceptible of many changes and modifications within thespirit and scope thereof, and I therefore do not wish to be limited tothe details shown and described herein, but intend to cover all suchchanges and modifications as are encompassed by the scope of theappended claims.

I claim:

1. A rotary piston internal combustion engine of trochoidal constructioncomprising housing means, output shaft means provided with eccentricmeans, piston means carrying out a rotary movement within said housingmeans about said eccentric means, and means includingtrochoidally-shaped cam means at one of the two parts consisting of saidhousing means and said piston means and guide roller means at the otherof said two parts cooperating with said cam means for imparting to saidpiston means a predetermined relative rotary movement with respect tosaid output shaft means, said guide roller means including a pluralityof pairs of guide rollers, said cam means being subdivided into twopartial cam sections cooperating with pairs of guide rollers, saidpartial cam sections being disposed one behind the other in the axialdirection of the engine, one of said partial cam sections being inoperative engagement with one guide roller of a respective pair of guiderollers during occurrence of relatively large roller rotational speedsupon rotation of the piston means and the other partial cam sectionbeing in operative engagement with the other guide roller of arespective pair during the occurrence of relatively small rollerrotational speeds upon rotation of said piston means.

2. A rotary piston internal combustion engine of trochoidal constructioncomprising housing means, output shaft means provided with eccentricmeans, piston means carrying out a rotary movement within said housingmeans about said eccentric means, and means includingtrochoidally-shaped cam means at one of the two parts consisting of saidhousing means and said piston means and guide roller means at the otherof said two parts cooperating with said cam means for imparting to saidpiston means a predetermined relative rotary movement with respect tosaid output shaft means, said guide roller means including a pluralityof pairs of guide rollers, said cam means being subdivided into twopartial cam sections eooperating with pairs of guide rollers, saidpartial cam sections being disposed one behind the other in the axialdirection of the engine.

3. A rotary piston internal combustion engine of troehoidal constructioncomprising housing means, output shaft means provided with eccentricmeans, piston means carrying out a rotary movement within said housingmeans about said eccentric means, and means includingtrochoidally-shaped cam means at one of the two parts consisting of saidhousing means and said piston means and guide roller means at the otherof said tWo parts cooperating with said cam means for imparting to saidpiston means a predetermined relative rotary movement with respect tosaid output shaft means, said guide roller means including a pluralityof pairs of guide rollers, said cam means being subdivided into twopartial cam sections cooperating with pairs of guide rollers, saidpartial cam sections cooperating with pairs of guide rollers, saidpartial cam sections being disposed one behind the other in the axialdirection of the engine, one of said partial cam sections being inoperative engagement with one guide roller of a respective pair of guiderollers during occurrence of relatively large roller rotational speedsupon rotation of the piston means and the other partial cam sectionbeing in operative engagement with the other guide roller of arespective pair during the occurrence of relatively small rollerrotational speeds upon rotation of said piston means, the inactivesurface portions of the partial cam sections which remain out of contactwith said guide rollers being set-back with respect to the activesurface portions coming into engagement with said guide rollers.

4. A rotary piston internal combustion engine of trochoidal constructioncomprising housing means, output shaft means provided with eccentricmeans, piston means carrying out a rotary movement within said housingmeans about said eccentric means, and means includingtrochoidally-shaped cam means at one of the two parts consisting of saidhousing means and said piston means and guide roller means at the otherof said two parts cooperating with said cam means for imparting to saidpiston means a predetermined relative rotary movement with respect tosaid output shaft means, said guide roller means including a pluralityof pairs of guide rollers, said partial cam sections being disposed onebehind the other in the axial direction of the engine, one of saidpartial cam sections being in operative engagement with one guide rollerof a respective pair of guide rollers during occurrence of relativelylarge roller rotational speeds upon rotation of the piston means and theother partial cam section being in operative engagement with the otherguide roller of a respective pair during the occurrence of relativelysmall roller rotational speeds upon rotation of said piston means, andthe beginning and end of the active surface portions of the partial camsections being operatively connected with each other by web portionsoperative to engage both guide rollers of a respective guide rollerpair.

5. In a rotary piston internal combustion engine having a housing, arotary piston adapted to carry out a rotary movement within said housingabout an eccentric provided at the output shaft, and transmission meansconsisting of cam means and guide roller means for imparting to saidrotary piston a predetermined relative rotary movement with respect tosaid output shaft, the improve-. ment essentially consisting ofsubdividing said cam means into several partial cam sections disposedone behind the other in the axial direction of the engine, each guideroller means being constituted by several guide rollers, each guideroller of a respective guide roller means cooperating with a respectivepartial cam section in such a manner as to minimize accelerations anddecelerations on the part of said rollers.

6. A rotary piston internal combustion engine of trochoidal constructioncomprising housing means, output shaft means provided with eccentricmeans, piston means carrying out a rotary movement within said housingmeans about said eccentric means, and means includingtrochoidally-shaped cam means at one of the two parts consisting of saidhousing means and said piston means and guide roller means at the otherof said two parts cooperating with said cam means for imparting to saidpiston means a predetermined relative rotary movement with respect tosaid output shaft means, said guide roller means including a pluralityof pairs of guide rollers, said cam means being subdivided into twopartial cam sections cooperating with pairs of guide rollers, saidpartial cam sections being disposed one behind the other in the axialdirection of the engine, one of said partial cam sections being inoperative engagement with one guide roller of a respective pair of guiderollers during occurrence of relatively large roller rotational speedsupon rotation of the piston means and the other partial cam sectionbeing in operative engagement with the other guide roller of arespective pair during the occurrence of relatively small rollerrotational speeds upon rotation of said piston means, the inactivesurface portions of the partial cam sections which remain out of contactwith said guide rollers being set-back with respect to the activesurf-ace portions coming into engagement with said guide rollers, andthe beginning and end of the active surface portions of the partial earnsections being operatively connected with each other by web portionsoperative to engage both guide rollers of a respective guide rollerpair.

7. In a rotary piston internal combustion engine having a housing, arotary piston adapted to carry out a rotary movement within said housingabout an eccentric provided at the output shaft, and transmission meansconsisting of cam means and guide means cooperating with said cam meansfor imparting to said rotary piston a predetermined relative rotarymovement with respect to said output shaft, the improvement essentiallyconsisting in subdividing said cam means into partial cam means, eachguide means including a plurality of guide roller means, a respectiveguide roller means cooperating with a corresponding partial cam means insuch a manner as to minimize accelerations and decelerations on the partof said roller means.

8. A rotary piston internal combustion engine of trochoidal constructioncomprising housing means, output shaft means provided with eccentricmeans, piston means carrying out a rotary movement within said housingmeans about said eccentric means, means including troehoidallyshaped cammeans at one of the two parts consisting of said housing means andpiston means and guide roller means at the other of said two partscooperating with said cam means for imparting to said piston means thepredetermined relative rotary movement with respect to said output shaftmeans, and means in at least one of said cam and guide means forminimizing accelerations and decelerations of said guide means.

9. in a rotary piston internal combustion engine having a housing, arotary piston adapted to carry out a rotary movement within said housingabout an eccentric provided at the output shaft, and transmission meansconsisting of cam means and guide roller means for imparting to saidrotary piston a predetermined relative rotary movement with respect tosaid output shaft, the improvement essentially consisting of meansoperatively associated with said cam means and guide roller means tominimize accelerations and decelerations on the part of said rollermeans.

10. A rotary piston internal combustion engine of trochoidalconstruction comprising housing means, output shaft means provided witheccentric means, piston means carrying out a rotary movement within saidhousing means about said eccentric means, means includingtrochoidallyshaped cam means at one of the two parts consisting of saidhousing means and piston means and guide roller means at the other ofsaid two parts cooperating with said cam means for imparting to saidpiston means the predetermined relative rotary movement with respect tosaid output shaft means, and means in said cam and guide means forminimizing accelerations and decelerations of said guide means includinga plurality of partial cam sections in said cam means cooperating withguide rollers of said guide means;

11. ,A rotary piston internal combustion engine of trochoidalconstruction comprising housing means, output shafit means provided witheccentric means, piston means carrying out a rotary movement within saidhousing means about said eccentric means, means includingtrochoidally-shaped cam means at one of the two parts consisting of saidhousing means and piston means and guide roller means at the other ofsaid two parts cooperating with said cam means for imparting to saidpiston means the predetermined relative rotary movement with respect tosaid output shaft means, and means in said cam and guide means torminimizing accelerations and decelerations of said guide means includinga plurality of partial cam sections in said cam means cooperating withguide rollers of said guide means, said cam sections being disposed onebehind the other in the axial direction of the engine and being soarranged and constructed that one of said cam sections is in operativeengagement with one guide roller during occurrence of relatively largeroller rotational speeds upon rotation of the piston means and anothercam section is in operative engagement with another guide roller duringthe occurrence of relatively small roller rotational speeds uponrotation of said piston means.

No references cited.

1. A ROTARY PISTON INTERNAL COMBUSTION ENGINE OF TROCHOIDAL CONSTRUCTIONCOMPRISING HOUSING MEANS, OUTPUT SHAFT MEANS PROVIDED WITH ECCENTRICMEANS, PISTON MEANS CARRYING OUT A ROTARY MOVEMENT WITHIN SAID HOUSINGMEANS ABOUT SAID ECCENTRIC MEANS, AND MEANS INCLUDINGTROCHOIDALLY-SHAPED CAM MEANS AT ONE OF THE TWO PARTS CONSISTING OF SAIDHOUSING MEANS AND SAID PISTON MEANS AND GUIDE ROLLER MEANS AT THE OTHEROF SAID TWO PARTS COOPERATING WITH SAID CAM MEANS FOR IMPARTING TO SAIDPISTON MEANS A PREDETERMINED RELATIVE ROTARY MOVEMENT WITH RESPECT TOSAID OUTPUT SHAFT MEANS, SAID GUIDE ROLLER MEANS INCLUDING A PLURALITYOF PAIRS OF GUIDE ROLLERS, SAID CAM MEANS BEING SUBDIVIDED INTO TWOPARTIAL CAM SECTIONS COOPERATING WITH PAIRS OF GUIDE ROLLERS, SAIDPARTIAL CAM SECTIONS BEING DISPOSED ONE BEHIND THE OTHER IN THE AXIALDIRECTION OF THE ENGINE, ONE OF SAID PARTIAL CAM SECTIONS BEING INOPERATIVE ENGAGEMENT WITH ONE GUIDE ROLLER OF A RESPECTIVE PAIR OF GUIDEROLLERS DURING OCCURRENCE OF RELATIVELY LARGE ROLLER ROTATIONAL SPEEDSUPON ROTATION OF THE PISTON MEANS AND THE OTHER PARTIAL CAM SECTIONBEING IN OPERATIVE ENGAGEMENT WITH THE OTHER GUIDE ROLLER OF ARESPECTIVE PAIR DURING THE OCCURRENCE OF RELATIVELY SMALL ROLLERROTATIONAL SPEEDS UPON ROTATION OF SAID PISTON MEANS.